1. Field of Invention
Embodiments relate to a method of manufacturing an electronic device. More specifically, embodiments relate to a method of manufacturing a three-dimensional semiconductor device.
2. Description of Related Art
Nonvolatile memory devices are memory devices in which data stored therein is maintained even when a power supply is interrupted. Recently, due to an increase in the degree of integration, two-dimensional memory devices in which memory cells are formed in a single layer on a silicon substrate, are reaching physical limits, and three-dimensional nonvolatile memory devices in which memory cells are vertically stacked on a silicon substrate have been proposed.
In the three-dimensional memory devices, a stacked structure is formed by alternately stacking conductive layers and insulating layers, and a channel layer passing through the stacked structure is formed. Accordingly, a plurality of memory cells may be formed at the same time. In particular, memory strings are arranged in a U shape to improve the degree of integration of a memory device.
However, as the height of the stacked structure increases, difficulties in performing an etch process may increase. In addition, when the memory strings are arranged in the U shape, cell currents may decrease since a channel length increases. Furthermore, during a program or erase operation, operation characteristics may be degraded since currents which flow through the channel are not sufficient.